• 한국정밀공학회지
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• 제33권5호
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• pp.357-362
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• 2016

Various species of insects display vivid colors, widely known as 'structural color' due to their optical interference. Morpho butterflies are famous for their brilliant iridescent colors, which arise from the photonic-nanostructures of optical interference on their wings. In this paper, we outline the results of a comparative study of the optical properties of bio-inspired Morpho butterfly structures with the widely known Distributed Bragg Reflector (DBR), conducted using a rigorous coupled-wave analysis (RCWA) method for the two structures. Almost analogous tendencies were observed for both Morpho and DBR structures. With variation in the surrounding media, however, Morpho structures showed an obvious peak shift while no significant changes were observed in DBR, which can be applicable.

• Journal of the Optical Society of Korea
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• 제19권3호
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• pp.297-302
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• 2015

Terahertz (THz) wave generation from bulk and periodically poled $LiTaO_3$ (PPLT) with a Cherenkov phase matching scheme is numerically investigated. It is shown that by using the crystal birefringence of bulk $LiTaO_3$ and a grating vector of PPLT, THz waves can be efficiently generated by difference frequency generation (DFG) with a Cherenkov phase matching scheme. The frequency tuning characteristics of the THz wave via varying wavelength of difference frequency waves, phase matching angle, poling period of PPLT and working temperature are theoretically analyzed. The parametric gain coefficient in the low-loss limit and the absorption coefficient of the THz wave during the DFG process in the vicinity of polariton resonances are numerically analyzed. A THz wave can be efficiently generated by utilizing the giant second order nonlinearities of $LiTaO_3$ in the vicinity of polariton resonances.

• 반도체디스플레이기술학회지
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• 제5권4호
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• pp.1-4
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• 2006

Recently, with rapid development of digital media like semiconductor and large flat panel display, the manufacturing equipment is required to have high precision over large travel range. Moreover it should have high product throughput. To achieve high product throughput, a controller should perform fast point-to-point motion and high precision positioning after settling in spite of external disturbances or residual vibrations. We proposed a new mode switching control algorithm with an application to dual stage for long range and high precision positioning. The proposed algorithm uses a proximate time-optimal servomechanism for the fast settling and a time-delay controller for the high precision positioning. Experimental results show that the proposed method enables smooth mode switching and improves the settling time and the precision accuracy after settling by over than 33% and 45%, respectively.

• 전기전자학회논문지
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• 제20권1호
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• pp.61-67
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• 2016

본 논문에서는 중성자 방사선 측정을 위한 고속 고정밀 중성자 측정을 위한 하드웨어 설계방법을 제안한다. 제안된 고속 고정밀 중성자 측정 장치의 하드웨어 설계는 고성능 A/D 변환기를 사용하여 고정밀 고속의 아날로그 신호를 디지털 데이터로 변환할 수 있도록 구성된다. 중성자 센서를 사용하여 입사된 중성자 방사선 입자를 검출하고, 극저전류 정밀 측정 모듈을 통해 검출된 중성자 방사선을 보다 정밀하고 빠르게 측정하는 모듈을 설계한다. 고속 고정밀 중성자 측정을 위한 하드웨어 시스템은 중성자 센서부, 가변 고전압 발생부, 극저전류 정밀 측정부, 임베디드 시스템부, 디스플레이부 등으로 구성 된다. 중성자 센서부는 고밀도 폴리에틸렌을 통해 중성자 방사선을 검출하는 기능을 수행한다. 가변 고전압 발생부는 중성자 센서가 정상적으로 운영되기 위하여 발열 및 잡음 특성에 강인한 0 ~ 2KV 가변 고전압 발생장치의 기능을 수행한다. 극저전류 정밀 측정부는 중성자 센서에서 출력되는 고정밀 고속의 극저전류 신호를 고성능 A/D 변환기를 사용하여 정밀하고 빠르게 측정하고 아날로그 신호를 디지털 신호로 변환하는 기능을 수행한다. 임베디드 시스템부는 고속 고정밀 중성자 측정을 위한 중성자 방사선 측정 기능, 가변 고전압 발생장치 제어 기능, 유무선 통신 제어 기능, 저장 기능 등을 수행한다. 제안된 고속 고정밀 중성자 측정을 위한 하드웨어를 실험한 결과, 불확도, 중성자 측정 속도, 정확도, 중성자 측정 범위 등에서 기존의 장치보다 우수한 성능이 나타남을 확인할 수가 있다.

• 한국항행학회논문지
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• 제23권4호
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• pp.316-321
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• 2019

본 논문에서는 정전류(constant current) 원리를 적용하여 각종 전기재료의 특정 대역 고정밀 임피던스 측정이 가능한 임피던스 측정 시스템을 마이크로프로세서를 사용하여 개발한다. 본 측정 시스템 보드에는 임피던스 측정장치를 포함하여 외부장치에서 디지털 데이터 취득을 위한 인터페이스 장치를 갖추고 있으며, 이와 같은 임베디드 보드에서 실행되는 펌웨어 프로그램으로 시스템 소프트웨어를 작성한다. 그리고 15-비트 ADC (analog-to digital converter)를 사용하여 특정 대역의 정밀 임피던스를 1/32768 정밀도로 측정하여 소수점 5자리까지 연산하여 출력할 수 있으며, 디지털 데이터를 관리하기 위해 개발된 측정장치와 일반 컴퓨터의 USB 인터페이스를 통해 데이터를 전송하여, 여타 측정 장비들 보다 범용적이고 사용이 용이한 인터페이스가 가능한 통신기능을 탑재한 임피던스 측정시스템을 개발하고 그 정밀도를 측정하여 검증한다.

• 한국정밀공학회지
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• 제30권6호
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• pp.589-595
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• 2013

Solution processed conjugated molecules enable to manufacture various electronic devices by unconventional and cost effective patterning methods as screen or gravure printing. Spin-coating is the most popularly used method to form conjugated polymeric film for various electronic devices. The coating method has certain disadvantages such as a large amount of unwanted wastes, difficulty forming a film with a large area, and impossible to apply roll-to-roll manufacturing. We present here a promising alternative coating method, bar-coating for conjugated polymer film and OLED with the bar coated light emitting layer. In this papers, we show atomic force microscope images of spin- and bar-coated Poly[(9,9-di-n-octylfluorenyl-2,7-diyl)-alt-(benzo[2,1,3]thiadiazol-4,8-diyl)] (F8BT) films on substrate. The bar-coated film showed a slight lower RMS roughness (1.058 [nm]) than spin-coated film (1.767 [nm]). It means the bar-coating is suitable method to form light emitting layers in OLEDs. By using bar-coating process, an OLED obtained with 4.7 [cd/A] in maximum current efficiency.

• 한국정밀공학회지
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• 제30권7호
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• pp.702-708
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• 2013

The white-light scanning interferometer (WSI) is an effective optical measurement system for high-precision industries (e.g., flat-panel display and electronics packaging manufacturers) and semiconductor manufacturing industries. Its major disadvantages include a slow image-capturing speed for interferogram acquisition and a high computational cost for peak-detection on the acquired interferogram. Here, a WSI system is proposed for the semiconductor inspection process. The new imaging acquisition technique uses an 'on-the-fly' imaging system. During the vertical scanning motion of the WSI, interference fringe images are sequentially acquired at a series of pre-defined lens positions, without conventional stepwise motions. To reduce the calculation time, a parallel computing method is used to link multiple personal computers (PCs). Experiments were performed to evaluate the proposed high-speed WSI system.

• 전자공학회논문지
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• 제49권10호
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• pp.23-33
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• 2012

본 논문은 위성항법시스템을 이용한 정밀 단독측위에 관한 연구이다. 위성항법시스템이 가지고 있는 내재적인 문제점인 장애물 등 여러 가지 환경 요인으로 인해 신호를 수신할 수 없는 경우 음영지역과 위치오차 증가 등에 관한 연구논문이다. 논문에서는 다양한 수신기의 성능 분석과 대도로 중앙, 대도로 측면, 주택가, 고층 건물 주변의 골목길 등 다양한 환경에 따른 위성수와 DOP(Dilution of Precision)변화 그리고 위치오차의 변화 등을 분석하였다. 그리고 환경 변화에 따른 위치오차 발생 범위와 오차 원인을 파악하여, 위성항법시스템의 신뢰성과 안정성을 높이는데 그 목적이 있다.

• Journal of Power Electronics
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• 제16권3호
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• pp.840-848
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• 2016

A primary-side regulation AC-DC converter operating in the PFM (Pulse Frequency Modulation) mode with a high precision output current is designed, which applies a novel inductance compensation technique to improve the precision of the output current, which reduces the bad impact of the large tolerance of the transformer primary side inductance in the same batch. In this paper, the output current is regulated by the OSC charging current, which is controlled by a CC (constant current) controller. Meanwhile, for different primary inductors, the inductance compensation module adjusts the OSC charging current finely to improve the accuracy of the output current. The operation principle and design of the CC controller and the inductance compensation module are analyzed and illustrated herein. The control chip is implemented based on a TSMC 0.35μm 5V/40V BCD process, and a 12V/1.1A prototype has been built to verify the proposed control method. The deviation of the output current is within ±3% and the variation of the output current is less than 1% when the inductances of the primary windings vary by 10%.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 학술대회지
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• pp.628-635
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• 2004

The characteristic of thin film resistor with low TCR( temperature coefficient of resistance ) and high precision are studied. The thin film resistor for 1/4W was fabricated and characteristic of these resistors was investigated. The fabricated device had the thickness of $2.48{\leqq}$ and the resistivity of $0.27{\omega}mm$. The electrical characteristic was evaluated by HP 4339B and 4284A instruments with HP l6339A. The profile of trimmed structure was also measured by non contact interferometer. The change of resistance and TCR increased with increasing roughness and resistance. To reduce the effect of stress annealing treatment was performed in the range of 563 to 623 K after trimming. The characteristic was improved after annealing. It is expected the fabricated device can be useful for high precision and low TCR. Fabricated thin film resistor has average deviation of resistance less than $0.35{\%}$ and TCR within 60.60ppm/K.